Quotas and Constraints¶
You can create dedicated and shared load balancers on ELB console. This section describes the quotas and restrictions that apply to ELB resources.
ELB Resource Quotas¶
Quotas put limits on the number or amount of resources, such as the maximum number of ECSs or EVS disks that you can create.
Table 1 lists the default quotas of ELB resources. You can view your quotas by referring to Quotas.
If the existing resource quota cannot meet your service requirements, you can request an increase to adjust quotas by referring to Quotas.
Resource | Description | Default Quota |
|---|---|---|
Load balancers | Load balancers per account | 50 |
Listeners | Listeners per account | 100 |
Forwarding policies | Forwarding policies per account | 500 |
Backend server groups | Backend server groups per account | 500 |
Certificates | Certificates per account | 120 |
Backend servers | Backend servers per account | 500 |
Listeners per load balancer | Listeners that can be added to a load balancer | 50 |
Note
The quotas apply to a single account.
Other Quotas¶
In addition to quotas described in ELB Resource Quotas, some other resources that you can use are also limited.
You can call APIs to query quotas of the resources described in Table 2 by referring to the "Querying Quotas" section in Elastic Load Balance API Reference.
Resource | Description | Default Quota |
|---|---|---|
Forwarding rules per forwarding policy | Forwarding rules that can be added to a forwarding policy | 10 |
Backend servers per backend server group | Backend servers that can be added to a backend server group | 500 |
IP address groups per load balancer | IP address groups per account | 50 |
Listeners per IP address group | Listeners that can be associated with an IP address group | 50 |
IP addresses per IP address group | IP addresses that can be added to an IP address group | 300 |
Load Balancer¶
Before creating a load balancer, you must plan its region, type, protocol, and backend servers. For details, see Preparations for Creating a Load Balancer.
The size of files that a load balancer can forward:
Layer 4 listeners: any
Layer 7 listeners: 10 GB or smaller
Listener¶
The listener of a dedicated load balancer can be associated with a maximum of 50 backend server groups.
An SNI certificate can have up to 100 domain names separated by commas (,).
SNI certificates of a dedicated load balancer's listener can have up to 200 domain names.
SNI certificates of a shared load balancer's listener can have up to 30 domain names.
An HTTPS listener can have up to 30 SNI certificates.
Once set, the frontend protocol and port of the listener cannot be modified.
Forwarding Policy¶
Forwarding policies can be configured only for HTTP and HTTPS listeners.
Forwarding policies must be unique.
A maximum of 100 forwarding policies can be configured for a listener. If the number of forwarding policies exceeds the quota, the excess forwarding policies will not be applied.
Forwarding conditions:
If the advanced forwarding policy is not enabled, each forwarding rule has only one forwarding condition.
If the advanced forwarding policy is enabled, each forwarding rule has up to 10 forwarding conditions.
Load Balancer Type | Advanced Forwarding | Forwarding Rule | Action |
|---|---|---|---|
Shared | Not supported | Domain name and URL | Forward to another backend server group and Redirect to another listener |
Dedicated | Disabled | Domain name and URL | Forward to another backend server group and Redirect to another listener |
Enabled | Domain name, URL, HTTP request method, HTTP header, query string, and CIDR block | Forward to a backend server group, Redirect to another listener, Redirect to another URL, and Return a specific response body |
Backend Server Group¶
The backend protocol of the backend server group must match the frontend protocol of the listener as described in Table 4.
Frontend Protocol | Backend Protocol |
|---|---|
TCP | TCP |
UDP |
|
HTTP | HTTP |
HTTPS |
|
Backend Server¶
If Transfer Client IP Address is enabled, a server cannot serve as both a backend server and a client.
TLS Security Policy¶
You can create a maximum of 50 TLS security policies.